A scale model net test of the operation of a small two-boat midwater trawl net was performed in the circulating water tank at Pusan Fisheries College. The 1/32 scale model net was constructed after the modelling law of M. Tauti. This type of net is used in Europe for catching sprat like Hering. The net used was 1/32 the actual size. This scale was chosen with consideration for the water tank size. In this experiment, the transfomation of the net shape was observed especially inregard to variations in the height and breadth of the net mouth. These dimensions were varied by changing the breadth of the towing line and the connenting spread.